An apparatus for a steam engine is known in the art, for example as disclosed in Japanese Patent Publication No. H7-180649, in which energy is obtained by repeating vaporization and liquefaction of fluid.
In the above apparatus, volatile fluid is filled in a heating chamber, wherein the fluid is vaporized by heating the same and vaporized fluid is introduced into a vertically arranged fluid pipe and guided to an upper portion of the fluid pipe. Then, the vaporized fluid is cooled and liquidized in a cooling chamber provided at the upper portion of the fluid pipe. The liquidized fluid returns to the heating chamber through the fluid pipe. A magnetic member is provided the fluid pipe to cause a movement thereof. An electric power is generated by producing electromotive force at a coil provided at an outside of the fluid pipe.
The applicant of the present invention has proposed a steam engine, as disclosed in Japanese Patent Publication No. 2002-245165 (which corresponds to U.S. patent Publication No. 2004/0060294 A1), in which working fluid in a fluid container is vibrated in a self-excited vibrating manner as a result of a repeated operation of vaporization and liquefaction of the working fluid by heating and cooling the working fluid. And a driving force is obtained from the fluid vibration and finally an electric power is generated by such driving force.
The above steam engine 500 is shown in FIG. 7, which comprises a fluid container 502 having a circular fluid passage, a heating device 504 for heating working fluid in the fluid container 502, a cooling device 506 arranged above the heating device 504 and cooling steam vaporized at the heating device 504, and an output device 508. The output device 508 comprises a cylinder 510, a piston 512 silidably moving back and forth in the cylinder 510, a moving member 514 connected at its one end to the piston 512, and a spring 516 connected to the other end of the moving member 514. The piston 512 is moved in the cylinder 510 in a reciprocating manner in accordance with pressure from the working fluid.
In the above steam engine 500, volumetric expansion of the working fluid occurs in the fluid container 502, when the working fluid is heated and vaporized by the heating device 504. The vaporized steam heated at the heating device 504 moves upwardly toward the cooling device 506, at which the steam is cooled and liquidized. Volumetric contraction of the working fluid in the fluid container 502 occurs by the liquefaction of the working fluid. The piston 512 and the moving member 514 of the output device 508 are reciprocated by change of liquid surface (self-excited vibration) as the pressure change due to the volumetric expansion and contraction of the working fluid in the fluid container 502.
Accordingly, electromotive force is generated and thereby electric power can be generated by the reciprocal movement of the piston 512 and the moving member 514, when a permanent magnet is fixed to the moving member 514 and a coil is provided at a position opposing to the permanent magnet.
It is, however, disadvantageous in the above steam engine 500, in that thermal efficiency is not sufficiently high.
Namely, when the vaporized steam produced at the heating device 504 moves upwardly, liquid-phase working fluid directly below the steam also moves upwardly and passes through the heating device 504, so that such working fluid may be heated by the heating device 504 to a temperature at which the fluid can not be vaporized.
In the case that the working fluid passing through the heating device 504 is heated but not vaporized, thermal energy supplied to the working fluid passing through the heating device 504 as the liquid-phase working fluid does not contribute to the volumetric expansion of the working fluid in the fluid container 502, and thereby such energy can not be used for the reciprocal movement of the piston 512 and the moving member 514.
As above, a part of the thermal energy is unnecessarily wasted in the above steam engine 500, the thermal efficiency is decreased corresponding to such wasted thermal energy.